J. Chem. Eng. Data 1997, 42, 187-189
187
Apparent Molar Volumes of Strontium Chloride in Ethanol + Water at 298.15 K M. Pilar Pen ˜ a, Ernesto Vercher, and Antoni Martı´nez-Andreu* Departamento de Ingenierı´a Quı´mica, Facultad de Quı´mica, Universitat de Vale`ncia, 46100 Burjassot, Valencia, Spain
Densities of ethanol + water + strontium chloride mixtures have been measured with an oscillatingtube densimeter over a large range of concentrations of the salt and ethanol, at 298.15 K. From these densities, apparent molar volumes of the electrolyte in these mixtures have been calculated, and partial molar volumes at infinite dilution have been evaluated.
Introduction Density data on electrolyte solutions furnish some interesting information in elucidating the structural interactions occurring in solution. Most density measurements have been made on aqueous as well as nonaqueous electrolyte solutions. Comparatively, less attention has been devoted to densities of ternary mixtures (water + nonaqueous solvent + electrolyte), possibly due to the large quantity of experimental work necessary. The effect of a salt dissolved in a mixed solvent has potential application in the recovery of organic liquids from aqueous solutions by distillation. The study of density data for a mixed solvent containing electrolytes provides some preliminary information concerning the salt effect on vapor-liquid equilibria. In a previous work (Pen˜a et al., 1995a), we studied the vapor-liquid equilibrium of the ethanol + water + strontium chloride system. In the present work, we have determined the densities of this system at 298.15 K and have obtained the apparent molar volumes of the strontium chloride in ethanol + water mixtures. Millero (1972) reported partial molar volumes at infinite dilution for the strontium chloride in water from Shedlovsky and Brown (1934), Kruis (1936), Redlich (1940), Wirth (1940), Fajans and Johnson (1942), and Ellis (1967). Furthermore, Herz (1914) published experimental density data of the water + strontium chloride binary system. Bateman (1949) gave apparent molar volume data for the strontium chloride in ethanol + water. The strontium chloride is not soluble in absolute ethanol. Experimental Section The chemicals were absolute ethanol (Baker analyzed reagent, >99.5 mass %), distilled water, and strontium chloride (Probus, >99.5 mass %). They were used without further purification. The density of ethanol was (785.08 ( 0.01) kg‚m-3 at 298.15 K, indicating a maximum of 0.01 vol % of water, as reported by Marsh and Richards (1980). The density of pure water at 298.15 K was taken as 997.05 kg‚m-3 (Marsh and Richards, 1980). The water + strontium chloride samples were analyzed gravimetrically, by evaporation to dryness. The accuracy of salt mole fractions in the samples was better than 0.000 01. The ethanol + water + strontium chloride mixtures were prepared one by one gravimetrically using a Sartorius analytical balance with a precision of (0.0001 * To whom correspondence
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Table 1. Densities d, Molar Volumes V, and Molar Concentrations c of Water (2) + Strontium Chloride (3) Mixtures and Apparent Molar Volumes VO of Strontium Chloride in Water at 298.15 K x3
d/kg‚m-3
V/cm3‚mol-1
c/mol‚L-1
Vφ/cm3‚mol-1
0.001 79 0.004 84 0.008 21 0.013 86 0.018 66 0.022 09 0.026 50 0.030 19 0.034 35 0.039 06 0.045 06 0.054 72 0.061 37
1010.77 1033.76 1058.79 1099.64 1133.87 1157.84 1188.37 1213.35 1241.22 1272.49 1311.07 1372.26 1413.31
18.073 18.086 18.105 18.154 18.202 18.241 18.293 18.344 18.404 18.471 18.571 18.732 18.849
0.0989 0.2678 0.4536 0.7633 1.0254 1.2109 1.4484 1.6458 1.8667 2.1147 2.4265 2.9214 3.2561
20.2 ( 0.8 21.6 ( 0.3 22.54 ( 0.17 24.23 ( 0.10 25.20 ( 0.08 25.84 ( 0.06 26.53 ( 0.05 27.20 ( 0.04 27.82 ( 0.04 28.37 ( 0.03 29.21 ( 0.03 30.19 ( 0.02 30.78 ( 0.02
g. They were stirred for sufficient time to assure dissolution of the salt and stored in vials prior to use. Samples were kept in a water bath at 303 K to prevent the formation of bubbles in the densimeter. The accuracy of ethanol and water mole fractions was better than 0.000 05, and the accuracy of salt mole fraction was better than 0.000 004. The mole fraction solubility of strontium chloride in water at 298.15 K is 0.0596 (Menzies, 1936) and decreases almost linearly when the mole fraction of ethanol in the mixed solvent increases, to become practically zero when the mole fraction of alcohol in the ethanol + water mixed solvent is 0.80. Therefore, no samples were prepared with a mole fraction of alcohol in the ethanol + water mixed solvent greater than 0.80. The sample densities were measured with an Anton Paar DMA 55 densimeter matched to a Julabo circulator with proportional temperature control and an automatic drift correction system that kept the samples at (298.15 ( 0.01) K. The densimeter was calibrated with distilled water and dry air. The accuracy of density values was (0.01 kg‚m-3. Results and Discussion In Table 1 the densities, d, of the water (2) + strontium chloride (3) mixtures are reported, where x3 is the mole fraction of strontium chloride in the binary mixture. In Table 2 the density, d, of the ethanol (1) + water (2) + strontium chloride (3) system is reported, where xi is the mole fraction of component i in the ternary mixture and x′1 is the mole fraction of ethanol in the salt-free solvent. From these results, the molar volume of solution, V, and the molar concentration of salt in the solution, c, were © 1997 American Chemical Society
188 Journal of Chemical and Engineering Data, Vol. 42, No. 1, 1997 Table 2. Densities d, Molar Volumes V, and Molar Concentrations c of Ethanol (1) + Water (2) + Strontium Chloride (3) Mixtures and Apparent Molar Volumes VO of Strontium Chloride in Ethanol + Water Mixtures at 298.15 K x1
x2
x3
x′1
d/kg‚m-3
V/cm3‚mol-1
c/mol‚L-1
Vφ/cm3‚mol-1
0.020 03 0.041 29 0.089 56 0.142 82 0.206 09 0.280 02 0.366 00 0.476 05 0.600 45 0.778 37 0.020 20 0.041 18 0.088 10 0.142 78 0.203 27 0.278 37 0.365 88 0.464 52 0.602 19 0.759 03 0.019 72 0.041 43 0.088 11 0.141 85 0.204 73 0.365 29 0.472 49 0.603 38 0.019 43 0.040 58 0.086 71 0.142 13 0.201 80 0.275 44 0.362 08 0.467 36 0.019 76 0.040 76 0.087 20 0.140 76 0.202 44 0.275 33 0.363 14 0.019 74 0.040 61 0.086 46 0.139 28 0.200 51 0.272 86 0.358 60 0.040 95 0.086 71 0.139 73 0.201 58 0.273 40 0.019 14 0.040 15 0.085 53 0.137 72 0.198 16 0.019 25 0.040 15 0.086 24 0.090 87 0.019 16 0.040 31 0.084 05 0.019 09
0.974 78 0.953 62 0.905 30 0.851 97 0.788 67 0.714 90 0.628 85 0.518 77 0.394 41 0.216 56 0.969 83 0.948 85 0.901 81 0.847 23 0.786 72 0.711 59 0.624 11 0.525 67 0.387 79 0.231 24 0.964 85 0.943 13 0.896 41 0.842 67 0.779 87 0.619 25 0.511 93 0.381 20 0.960 52 0.939 45 0.893 33 0.837 93 0.778 23 0.704 59 0.617 93 0.512 66 0.954 39 0.933 42 0.886 94 0.833 40 0.771 75 0.698 84 0.610 95 0.950 28 0.929 39 0.883 55 0.830 72 0.769 53 0.697 21 0.611 39 0.922 81 0.877 20 0.824 03 0.762 17 0.690 41 0.940 92 0.919 99 0.874 45 0.822 19 0.761 80 0.934 04 0.913 13 0.867 10 0.862 89 0.930 84 0.909 49 0.866 08 0.923 69
0.005 195 0.005 091 0.005 139 0.005 214 0.005 243 0.005 083 0.005 151 0.005 180 0.005 142 0.005 066 0.009 971 0.009 976 0.010 093 0.009 989 0.010 010 0.010 043 0.010 010 0.009 808 0.010 029 0.009 730 0.015 430 0.015 443 0.015 475 0.015 489 0.015 400 0.015 459 0.015 572 0.015 427 0.020 048 0.019 966 0.019 960 0.019 943 0.019 976 0.019 967 0.019 988 0.019 978 0.025 855 0.025 827 0.025 853 0.025 848 0.025 810 0.025 821 0.025 915 0.029 979 0.030 000 0.029 991 0.030 007 0.029 957 0.029 932 0.030 006 0.036 238 0.036 085 0.036 239 0.036 242 0.036 195 0.039 942 0.039 862 0.040 024 0.040 096 0.040 044 0.046 706 0.046 724 0.046 662 0.046 244 0.050 007 0.050 200 0.049 863 0.057 216
0.020 13 0.041 50 0.090 02 0.143 56 0.207 18 0.281 45 0.367 90 0.478 53 0.603 55 0.782 33 0.020 40 0.041 59 0.089 00 0.144 22 0.205 33 0.281 19 0.369 58 0.469 12 0.608 29 0.766 49 0.020 02 0.042 08 0.089 50 0.144 08 0.207 93 0.371 03 0.479 97 0.612 83 0.019 83 0.041 41 0.088 48 0.145 02 0.205 91 0.281 06 0.369 46 0.476 89 0.020 28 0.041 84 0.089 52 0.144 49 0.207 81 0.282 63 0.372 80 0.020 35 0.041 87 0.089 13 0.143 58 0.206 70 0.281 28 0.369 69 0.042 49 0.089 96 0.144 98 0.209 16 0.283 66 0.019 93 0.041 81 0.089 09 0.143 47 0.206 42 0.020 19 0.042 12 0.090 46 0.095 27 0.020 17 0.042 44 0.088 46 0.020 25
1026.04 1016.21 999.17 980.99 958.74 933.38 909.09 882.42 857.28 828.12 1059.99 1049.70 1030.77 1007.51 983.54 956.27 928.56 901.20 872.43 844.22 1097.94 1086.53 1063.75 1038.13 1009.12 949.74 919.34 888.72 1130.02 1116.73 1091.08 1062.14 1033.04 1000.38 969.01 935.57 1168.76 1154.38 1126.23 1094.87 1059.84 1025.52 990.75 1197.58 1181.15 1150.60 1116.31 1080.41 1043.71 1007.71 1219.17 1184.92 1149.38 1110.08 1071.40 1260.11 1242.01 1207.79 1169.14 1128.26 1303.35 1285.38 1244.52 1236.85 1324.88 1303.91 1263.47 1365.89
18.818 19.572 21.268 23.196 25.590 28.483 31.908 36.376 41.508 48.984 18.853 19.599 21.252 23.251 25.546 28.482 31.971 35.981 41.630 48.183 18.887 19.648 21.304 23.284 25.689 32.047 36.395 41.758 18.918 19.665 21.312 23.354 25.637 28.538 31.973 36.272 18.997 19.741 21.394 23.379 25.779 28.638 32.142 19.024 19.786 21.428 23.416 25.778 28.626 32.045 19.896 21.537 23.515 25.911 28.721 19.177 19.922 21.559 23.533 25.882 19.272 20.000 21.689 21.881 19.307 20.094 21.671 19.468
0.2761 0.2601 0.2416 0.2248 0.2049 0.1784 0.1614 0.1424 0.1239 0.1034 0.5289 0.5090 0.4749 0.4296 0.3919 0.3526 0.3131 0.2726 0.2409 0.2019 0.8169 0.7860 0.7264 0.6652 0.5995 0.4824 0.4279 0.3694 1.0597 1.0153 0.9366 0.8539 0.7792 0.6997 0.6252 0.5508 1.3610 1.3083 1.2084 1.1056 1.0012 0.9017 0.8063 1.5759 1.5162 1.3996 1.2815 1.1621 1.0456 0.9364 1.8214 1.6755 1.5411 1.3987 1.2602 2.0828 2.0009 1.8565 1.7038 1.5472 2.4235 2.3362 2.1515 2.1135 2.5900 2.4983 2.3010 2.9390
21.7 ( 0.3 21.6 ( 0.3 21.1 ( 0.3 23.2 ( 0.3 26.5 ( 0.3 27.6 ( 0.3 24.0 ( 0.4 24.2 ( 0.5 24.6 ( 0.6 14.9 ( 0.9 22.84 ( 0.15 22.94 ( 0.15 23.11 ( 0.15 26.22 ( 0.16 28.62 ( 0.16 28.92 ( 0.17 27.39 ( 0.19 28.47 ( 0.23 25.5 ( 0.3 18.1 ( 0.4 24.53 ( 0.10 23.84 ( 0.10 24.72 ( 0.10 27.65 ( 0.10 30.45 ( 0.10 30.19 ( 0.12 29.89 ( 0.15 27.41 ( 0.19 25.10 ( 0.08 24.86 ( 0.08 26.11 ( 0.08 28.48 ( 0.08 30.54 ( 0.08 31.77 ( 0.08 30.04 ( 0.09 31.34 ( 0.11 26.12 ( 0.06 26.04 ( 0.06 26.79 ( 0.06 28.97 ( 0.06 32.18 ( 0.06 32.52 ( 0.06 31.95 ( 0.07 25.91 ( 0.05 26.62 ( 0.05 27.60 ( 0.05 30.49 ( 0.05 32.59 ( 0.05 33.30 ( 0.05 32.80 ( 0.06 27.85 ( 0.04 28.74 ( 0.04 30.60 ( 0.04 32.55 ( 0.04 32.59 ( 0.04 28.35 ( 0.04 28.33 ( 0.04 29.31 ( 0.04 31.67 ( 0.04 33.68 ( 0.04 28.81 ( 0.03 28.49 ( 0.03 29.94 ( 0.03 30.65 ( 0.03 28.87 ( 0.03 29.53 ( 0.03 30.37 ( 0.03 30.36 ( 0.03
calculated. In Tables 1 and 2 we also report values of V and c. The apparent molar volume, Vφ, of strontium chloride in the ethanol + water mixture is defined from the molar volume of solution, V, as we deduced in a previous work (Pen˜a et al., 1995b), by means of the expression
E V ) V°1x1 + V°2x2 + V12 (x1 + x2) + Vφx3
(1)
where V°1 is the molar volume of pure ethanol, V°2 is that of E is the excess molar volume of the pure water, and V12 binary ethanol + water mixture, which depends on the solvent composition.
Journal of Chemical and Engineering Data, Vol. 42, No. 1, 1997 189 The apparent molar volume of strontium chloride in a ternary liquid mixture of ethanol + water + strontium chloride can be calculated, for each composition, by using eq 1, once the density of the sample, the molar volumes of pure ethanol and pure water, and the dependence on composition of the excess molar volume of the binary ethanol + water mixture, at the same pressure and temperature conditions, are known. E , for each composition of the solvent The value of V12 mixture, was calculated by using a correlation (Pen˜a et al., 1995b) obtained from experimental data published by Marsh and Richards (1980). The values of the apparent molar volume of strontium chloride calculated at 298.15 K are also shown in Tables 1 and 2. These values are significantly lower than the values reported by Bateman (1949). Millero (1971) and Nomura et al. (1985) suggested that the apparent molar volume of an electrolyte in a mixed solvent, at constant solvent composition, can be fitted by the Masson equation (1929):
Vφ ) V∞φ + Sevc1/2
(2)
where V∞φ is the apparent molar volume of strontium chloride at infinite dilution, which is the same as the partial molar volume of strontium chloride at infinite dilution, and Sev is the experimental slope. Both V∞φ and Sev depend on the solvent composition and can be correlated using the following expressions:
V∞φ /cm3‚mol-1 )
4
∑b (x′ ) ν
ν
(3)
1
ν)0
4
Seν/cm3‚mol-3/2‚L1/2 )
∑c (x′ )
ν
ν
1
(4)
ν)0
From the Vφ values of strontium chloride in water, given in Table 1, we have found that V∞φ ) 17.8 cm3‚mol-1. This value is in good agreement with the 17.94 cm3‚mol-1 value recommended by Millero (1972). The V∞φ values obtained from density data reported by Herz (1914) and Bateman (1949) are respectively 20.7 cm3‚mol-1 and 29.2 cm3‚mol-1. These values are out of the range suggested by Millero (1972). From the Vφ values and at a least-squares minimization, we have found the values of bν and cν that minimize the sum of the squares of deviations between experimental and calculated results of Vφ in the range 0.02 e x′1 e 0.8. These parameters are given in Table 3. The mean absolute deviation of the apparent molar volume for the strontium chloride is 0.63 cm3‚mol-1, and the standard deviation is 0.82 cm3‚mol-1. From the values of bν and cν and eqs 1-4, we have recalculated the molar volume and the density of the
Table 3. Parameters of Eqs 3 and 4 bν cν
ν)0
ν)1
ν)2
ν)3
ν)4
14.968 8.827
80.478 -52.706
-376.42 473.61
736.7 -1096.2
-516.3 777.7
ethanol + water + strontium chloride solutions. The mean absolute deviation of molar volume is 0.011 cm3‚mol-1, and the corresponding standard deviation is 0.015 cm3‚mol-1. The mean absolute deviation of the density is 0.52 kg‚m-3, and the standard deviation is 0.67 kg‚m-3. However, the apparent molar volumes of strontium chloride in pure water recalculated from eqs 1-4 with the parameters of Table 3 do not agree well with the values obtained from the experimental binary data. Literature Cited Bateman, R. L. The Apparent Molal Volume of Strontium Chloride in Ethanol-Water Mixtures. J. Am. Chem. Soc. 1949, 71, 2291-2293. Ellis, A. J. Partial Molal Volumes of MgCl2, CaCl2, SrCl2 and BaCl2 in Aqueous Solutions to 200 °C. J. Chem. Soc. A 1967, 4, 660-664. Fajans, K.; Johnson, O. Apparent Volumes of Individual Ions in Aqueous Solution. J. Am. Chem. Soc. 1942, 64, 668-678. Herz, W. The internal friction of salt solutions. Z. Anorg. Chem. 1914, 89, 393-396. Kruis, A. Dependence on Concentration of Apparent Molar Volumes of Single Strong Electrolytes. Z. Phys. Chem. 1936, B34, 1-12. Marsh, K. N.; Richards, A. E. Excess Volumes for Ethanol + Water Mixtures at 10-K Intervals from 278.15 to 338.15 K. Aust. J. Chem. 1980, 33, 2121-2132. Masson, D. O. Solute Molecular Volumes in Relation to Solvation and Ionization. Philos. Mag. 1929, 8, 218-235. Menzies, A. W. C. A Method for the Determination of the Solubility. Solubilities of the SrCl2-H2O System at 20-200 °C. J. Am. Chem. Soc. 1936, 58, 934-937. Millero, F. J. The Molal Volumes of Electrolytes. Chem. Rev. 1971, 71, 147-176. Millero, F. J. The Partial Molal Volumes of Electrolytes in Aqueous Solutions. In Water and Aqueous Solutions; Horne, R. A., Ed.; Wiley-Interscience: New York, 1972. Nomura, H.; Kawaizumi, F.; Miyahara, Y. Partial Molar Volumes of CaCl2 in Water-Methanol mixtures and the Applicability of the Debye-Hu¨ckel Theory. Chem. Eng. Commun. 1985, 34, 305-314. Pen˜a, M. P.; Vercher, E.; Martinez-Andreu, A. Isobaric Vapor-Liquid Equilibrium for Ethanol + Water + Strontium Chloride. J. Chem. Eng. Data 1995a, 40, 311-314. Pen˜a, M. P.; Vercher, E.; Martinez-Andreu, A. Partial Molar Volumes of Strontium Bromide in Ethanol + Water Mixtures at 298.15 K. J. Chem. Eng. Data 1995b, 40, 662-664. Redlich, O. Molal Volumes of Solutes IV. J. Phys. Chem. 1940, 44, 619629. Shedlovsky, T.; Brown, A. S. The Electrolytic Conductivity of Alkaline Earth Chlorides in Water at 25 °C. J. Am. Chem. Soc. 1934, 56, 1066-1071. Wirth, H. E. Density of Sea Water. J. Marine Res. 1940, 3, 230-247.
Received for review July 31, 1996. Accepted October 28, 1996.X Financial support by Generalitat Valenciana (Grant GV-1006/93) is gratefully acknowledged.
JE960260P X
Abstract published in Advance ACS Abstracts, December 1, 1996.
